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134

Forging Piston-rod.

especially the shearings of plates from the Boiler Yard, and this
being worked over and over again in the manner previously
described we naturally obtain a better quality of iron than that
which has been but once puddled. Another point to notice is
that the slabs should all he perfectly welded by good hammering
before the forging is actually formed to the required shape, for
much working after cutting to proper dimension will cause distor-
tion; while if, on the other hand, sufficient hammering is not
given to the slabs, cracks are sure to show after machining, and
the piece will be dangerously weak.

Fig. 127 will serve to shew the forging of the Piston-rod.
Its finished form is given at A, the cross-head being solid with the
rod, and having renewable ' slippers' of cast iron. Slabs are
piled on the porter to form the cross-head, as at B, first on one
side and then on the other; sufficient, if possible, to complete both